core: make category import compatible with WSGI

RESPONSE.write cannot be used with WSGI, so use another trick to return
a response without commiting the transaction.

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/CategoryTool_importCategoryFile.py

@@ -57,7 +57,8 @@ category_list_spreadsheet_dict = context.Base_getCategoriesSpreadSheetMapping(
 if detailed_report_result:
   REQUEST.other['portal_status_message'] = translateString('Spreasheet contains errors')
   REQUEST.other['category_import_report'] = detailed_report_result
-  REQUEST.RESPONSE.write(portal_categories.CategoryTool_viewImportReport().encode('utf-8'))
+  REQUEST.RESPONSE.setBody(portal_categories.CategoryTool_viewImportReport().encode('utf-8'), lock=True)
+  REQUEST.RESPONSE.setStatus(200, 'OK', lock=True)
   raise Exception('Spreadsheet contains errors')
 
 for base_category, category_list in category_list_spreadsheet_dict.iteritems():
@@ -209,8 +210,9 @@ if detailed_report:
   REQUEST.other['category_import_report'] = detailed_report_result
   result = portal_categories.CategoryTool_viewImportReport().encode('utf-8')
   if simulation_mode:
-    REQUEST.RESPONSE.write(result)
-    raise Exception('Dry run')  
+    REQUEST.RESPONSE.setBody(result, lock=True)
+    REQUEST.RESPONSE.setStatus(200, 'OK', lock=True)
+    raise Exception('Dry run')
   return result
 portal_categories.Base_redirect(
   keep_items={